This invention relates to a process for the production of custom-moulded ear inserts that are required for ear-level hearing aids and earmolds.
The shape of a custom mould is derived from an ear impression taken individually from the subject's ear. The ear impression is a negative replica of the ear.
There are currently two methods of impression shaping into custom moulds.
The older method is manual impression shaping. In this process, the impression is shaped manually by a technician with the use of mechanical cutters and grinders. The technician removes outer layers from the impression to achieve a mould shape suitable for a given custom product.
The newer method is computer-aided shaping of a digital ear image that is obtained by scanning of silicone impression, direct in-ear scanning, CT scanning, MRI scanning, or any volumetric imaging technique, and is further called a digital impression. In this process, the digital impression is virtually shaped with cutting and grinding tools available in the software.
Both the manual shaping and computer-aided modeling methods are time consuming, subjective, intuitive, and not free from inaccuracies. Inaccuracies in impression shaping result in ear moulds that have inadequate fit and are subsequently returned to the manufacturer with either a request for a new earpiece, or a request for a refund.
There are inventions that disclose automated processes where a pre-modelled shell stored in computer database is matched with a custom ear impression. This approach requires a large number of pre-modelled shells to cover the almost unlimited number of human ear shapes and sizes, and the great variety of custom hearing aid styles and options, which renders this concept impractical. In addition, a shell selected from a computer database is not a custom product.
U.S. patent Ser. No. 10/158,954 by Pirzanski discloses a virtual method for modeling the canal module from a digital impression with the use of 2D templates that feature a predetermined shape. In this method, two or more templates are inserted into the digital impression. Through motion, rotation and stretching the templates are matched with the contour of the ear canal. When positive matches are found, the templates are assembled into a 3D virtual frame, which is surfaced, and becomes the virtual canal module. The limitation of this method is that 2D templates are insufficient for modelling the concha area that features a sophisticated spatial form.
This disclosure describes an innovative method for concha virtual modeling that employs 3D customized modules.
This innovation provides the means of manufacturing custom product that is globally uniformed in physical fit and cosmetic appearance.